Sand-blast apparatus



G. c. FATscHER SAND BLAST APPARATUS March 19, 1929.

Filed May 17, 1925 iiiiili mom/frs Patented Mar. 19, 1929.

U'NiTED STATES PATENT oFFicE.

GEORGE C. FATSCHER, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO THE NEW HAVEN SAND BLAST COMPANY, OF NEW HAVEN, CONNECTICUT, A CORPORATION F CON- NECTICUT.

SAND-BLAST APPARATUS.

Application led May 17,

My invention relates to sand blast apparatus, and particularly to the construction of mixing chamber and adgacent structure.

rlhe general features of the present construction are shoivii in my copending application Ser. No. 700,280, tiled March 19, 1924, and the present invention relates to details of improvement designed first, to' insure proper feed opening for the abrasive to the blast in the mixing chamber; second, to tacilitate the removal of the mixing chamber liner fiom its casing; and third, to facilitate clean-out of the blast passage leading to the mixing chamber. l

In the accompanying drawings- .Fior 1 is a partial vertical section through a pressure tank sand blast apparatus in l Which my invention is embodied in one form; l

F ig. 2 is a section on the line 2-2, Fig. 1;

F ig. 8 is a section on the line 3 8, Fig. 2; and i Fig. 4 is a longitudinal section through the liner detached.

It suflices for an understanding of the present invention to referbriely to the pressure tank 15 which contains the abrasive 16 under pressure; the supporting ring 17 secured to the barrel bottom 18 and carrying the iniXing chamber casting 19 through the throat 20 of which sand passes from the barrel to the mixing chamber 35.

In my application above mentioned, the mixing chamber is provided with a later/- allv removable liner 21 which is ported at 22 to "admit sand from the throat 20 to the .blast passing through the liner. I have found that for abrasives of different character, for example-sand, grit, steel shot, ctc., the size of the port 22 should differ for each, if best results are to be attained. urthermore, the size of the port appropriate for a given abrasive should be constant, and regulation of feed should be accomplished by control of the relative pressures of the blast in the mixing chamber and upon the sand in the reservoir. I therefore provide a normally inaccessible gate slide 23 adapted to slide in a Way 2% out in the upper surface of the liner 21. At its forward end the slide 23 is provided with a beveled face 25 substantially parallel to the opposite beveled end of the port 22, so that in part-gate po 'ition the inclined port conditions are main- 1926. Serial No. 109,678.

tained to facilitate the feed of the sand by the suction effort of the blast passing the port, as explained in my application above mentioned. The opposite end of the slide is forked to straddle a clamping screw .26 which takes into the Wall of the liner and holds the slide in fixed position.

Inasmuch as the liner is completely housed ivithin the casting 19 under operating conditions, it is impossible for the operative to change the port opening, Without stopping the apparatus, removing the cover block 27 and taking out the liner. Preferably the margins of the port 22 are marked to indicate the proper setting of the gate for different abrasives. Once set in proper position the gate slide should not be changed so long as the saine type of abrasive is used, and as above stated the regulation of the loiv should be accomplished by manipulation of the valves which control the pressure upon the sand in the reservoir, and of the blast at the mixing chamber.

In using certain abrasives, particularly steel, grit or shot, there is very apt to be enough moisture carried into the mixing chamber, either by the abrasive or by the blast, to cause corrosion. lVhen this occiiis it is a very diflicult matter to remove the liner which becomes rusted in position. To facilitate its removal I have now provided in the wall of the mixing chamber opposite the cover block 27, a pair of ejector screivs 28. lyturning these in, after they bear upon the liner, the adhesion of the casting 19 may be readily broken. Instead of ejector screws it sulices to provide apertures normally closed by plugs. Upon removal of the plugs, a rod oi' pin may be inserted through the holes into engagement with the liner, whereupon a few taps of a hammer on the outer end of the rod will serve to free the liner, so that it may be readily removed.

A sudden back pressure in pipe 29 may be caused in various Ways, as for instance by the choking of the discharge nozzle. A sand slug may be built up in pipe 29 and may penetrate the entire horizontal length of the latter. In my previous construction the valve which controls the blast entering the mixing chamber is located at the junction between the pipes 29 and 30, and as a result it not infrequently happened that the valve became choked With sand. I have now y the plu@ the pipe section 29. I have also interposed a check valve 34 between the fitting 32 and the regulating valve 31.- As a result of this improved arrangement not only is a reduced amount. of sand thrown into the pipe 29 byV baclr pressure, but that which accumulates there may be readily removed by unscrewing g 33 and introducing a clean-out too of any appropriate character.

The practical improvements above de scribed may be readily varied in detail while accomplishing like results and without departing from what l claim as my invention.

I claiml. ln sand blast apparatus, a mixing chamber', a removable liner therefor, having a port in its upper wall, and a normally inaccessible slide gate carried by said liner for regulating the size of the port opening.

2. ln sand blast apparatus, a mixing chamber casing with a wall opening, a detachable Cap piece normally closingsaid wal opening, a liner adapted to be inserted and removed through said Vwall opening, the wallpof the casing opposite said opening being apertured to accommodate a liner ejecting means.

In sand blast apparatus, a mixing Chamber casing with a wall opening, a detachable cap piece normally closing said wall opening, a liner adapted. to be inserted and removed through said wall opening, the wall of the casing opposite said opening bcing' apertured to accommodate ejector screws.

In testimony whereof l have signed my name to this speciication.

GEORGE c. FATscHaR. 

